Mac mini crashing into the login screen. Anyone else experiencing the same and know of a solution?

I have a Mac mini (mid-2010) with 5GB of RAM and running OS X Lion 10.7.2 and lately I've been noticing it crash and take me directly to the login screen. After I sign back in everything reboots to where I left off. I believe the problem is related to Safari. I normally have many instances of Safari browser windows open and I'm wondering if that might be the issue? Is anyone else experiencing this problem and have they found any remedies?